You might unconsciously get eye diseases if you do not use the lenses properly.
Here are some bad examples below.
Example1. Handling the contact lenses with dirty hands.
They might cause some infections or allergies, so please wash your hands for sure before you wear/take off the lenses.
Example2. Wearing the contact lenses after applying makeup.
Example3. Rubbing the eyes while wearing contact lenses
Example4.Using the same contact lens case for a long time
Therefore you need to replace the case every 1.5 to 3 months(soft contact lens)/6 months to 1 year(hard contact lens).
Example5. Sleeping with contact lenses in your eyes
There are less tear production during sleep and that make the eyes dry, which increases the risk of your eyes getting dameged by the contact lenses.
Please see ophthalmologists if the eyes condition is bad after you wake up.
Example6. Overwearing contact lenses
Contact lenses are made on condition that you use them properly, so the conjunctiva or cornea might occur inflamation if you do not follow the rules.
The symptoms are often chronic and get worse gradually, so it’s difficult to be aware of them. Sometimes your symptoms might suddenly become severe too. Be sure to follow the rules and use contact lenses properly.
If you have used contact lenses in a wrong way and have any symptoms or concern, stop using them and go to an ophthalmologist.
Do you know how to wear/take off and care contact lenses?
If you use the lenses in a bad way, you might unconsciously get eye diseases.

However, if you have any symptoms, please see a doctor as soon as possible.